Pressure-sensitive record material

ABSTRACT

A PRESSURE-SENSITIVE RECORD UNIT COMPRISING SUPPORT SHEET MATERIAL HAVING MARK-FORMING COMPONENTS AND A PRESSURE-RELEASABLE LIQUID SOLVENT FOR SAID MARK-FORMING COMPONENTS ARRANGED IN CONTIGUOUS JUXTAPOSITION ON SAID SHEET MATERIAL, AT LEAST ONE OF THE MARK-FORMING COMPONENTS BEING MAINTAINED IN ISOLATION FROM THE OTHER MARKFORMING COMPONENT(S) PRIOR TO RELEASE OF THE SOLVENT, AND SAID MARK-FORMING COMPONENTS COMPRISING AT LEAST ONE   CHROMOGENIC MATERIAL AND AT LEAST ONE PHENOL-ALDEHYDE POLYMERIC MATERIAL SOLUBLE IN THE LIQUID SOLVENT AND REACTIVE WITH THE CHROMOGENIC MATERIAL TO PRODUCE A MARK.

June 27, 1972 R. E. MILLER ETA!- 3,672,935

PRESSURE-SENSITIVE RECORD MATERIAL Original Filed Aug. 27, 1964 3Sheets-Sheet l COATED ON REAR WITH MINUTE PRESSURE RUPTURABLE CAPSULESCONTAINING LIQUID SOLUTION OF CHROMOGENIC MATERIAL DEVELOPABLE ONCONTACT WITH POLYMER TO COLORED FORM RECEIVING SURFACE OF UNDERSHEETCOATED WITH POLYMER FIGJo INVENTORS ROBERT E. MILLER PAUL S'. PHILLIPS,JRJ

IJMLJ x M THEIR ATTOR NEYS.

June 27, 1972 MILLER EI'AL 3,672,935

PRESSURE-SENSITIVE RECORD MATERIAL Original Filed Aug. 27, 1964 3Sheets-Sheet 2 LEGEND F I G. 2

- CHROMOGENIC MATERIAL SOLID PARTICLES POLYMERIC REACTANT PARTICLES QLIQUID SOLVENT (ISOLATED) CHROMOGENIC MATERIAL REACTANT DISSOLVED INLIQUID soLvENTusOLATED) (9 POLYMERIC REACTANT OISSOLVED IN LIQuIOSOLVENTIISOLATEO) w w 3 3 PAPER H POLYMERIC CONTINUOUS COATING INVENTORSROBERT E.MILLER PAUL S. PHILLIPS, JR

19M, U,WRIW.

THEIR ATTORNEYS June 27, 1972 MILLER ETAL 3,672,935

PRESSURE-SENSITIVE RECORD MATERIAL Original Filed Aug. 27, 1964 3Sheets-Sheet 5 F l G. 2 (CONTINUED) w QM EEEEX 2&9?

INVENTORS I fi fiE sTlmfi'rs'ifim THEIR ATTORNEYS.

United States Patent Office 3,672,935 Patented June 27, 1972 3,672,935PRESSURE-SENSITIVE RECORD MATERIAL Robert E. Miller and Paul S.Phillips, Jr., Dayton, Ohio,

tasfiignors to National Cash Register Company, Dayton,

l Continuation of application Ser. No. 744,601, June 17, 1968, which isa continuation of application Ser. No. 392,404, Aug. 27, 1964. Thisapplication June 9, 1970, Ser. No. 44,805

Int. Cl. B41m /22 US. Cl. 11736.8 9 Claims ABSTRACT OF THE DISCLOSUREThis is a continuous application for that filed by the same applicantson June 17, 1968, under the provisions of the Commissioners Order forFiling Streamlined Continuation Applications appearing in volume 8240.6., page 1, which was given the Ser. No. 744,601 and a filing date ofJune 17, 1968, and which in turn was a continuation of originalapplication Ser. No. 392,404, filed Aug. 27, 1964, now abandoned.

This invention relates to an improved pressure-sensitive recordmaterial. More particularly, this invention relates to a novelmark-forming system wherein mark-forming components are brought, uponselective release of minute droplets of an isolated common solvent forsaid components, into mark-forming contact by solution in the releasedportion of said common solvent, and wherein one of the mark-formingcomponents is a polymer present in the pristine mark-forming recordmaterial prior to the'application of pressure.

In the past, there have been provided pressure-sensitive mark-formingunits and systems which comprised a chromogenic component, generallypresent as a solute in a liquid solvent which is the core or nucleusmaterial of a pressure-rupturable microcapsule, and an insoluble solidmark-forming component distributed in particulate form on a supportingsheet material, both components being arranged in proximate relation toeach other, so that, upon the application of marking pressure to acapsule, the capsule ruptures and releases the liquid-carriedchromogenic component, and the consequent contact of the mark-formingcomponents produces a mark or color in those regions where pressure isbrought to bear. In the most practiced form, the prior units and systemshad a micro-encapsulated solution of chormogenic material, such ascrystal violet lactone, distributed as isolated liquid droplets on theunder side of a supporting sheet, and a solid particulate material(namely, attapulgite clay) topcoated on an adjacent sheet. Upon ruptureof a capsule, the solution of chromogenic material migrated to and wasabsorbed by the nearby attapulgite particles to produce a mark accordingto the rupture pattern. 'In other prior systems, the capsules and theattapulgite were arranged on a single sheet.

While the aforementioned prior units and systems represented asubstantial advance over their predecessors,

experience has shown that exposure of the record material to ambientconditions oftentimes resulted in a desensitization of the attapulgiteparticles, believed to be caused by the take-up of atmosphericsubstances at the reactive sites present at the surface of the clayparticles, and consequent loss or diminution of its potential forreaction with the chromogenic material.

The present invention provides a pressure-sensitive mark-forming systemwhich is an improvement over the atmospheric-sensitive prior systems andwhich offers additional advantages, characterized hereafter. Broadlystated, the novel mark-forming system of this invention comprisesdisposing on and/or within sheet support material the unreactedmark-forming components (at least one of which is a polymeric material)and a liquid solvent in which each of the mark-forming components issoluble, said liquid solvent being present in such form that it ismaintained isolated by a pressure-rupturable barrier from atleast one ofthe mark-forming components until the application of pressure causes abreach in the barrier according to the pressure pattern, whereupon theliquid solvent is released according to the presure pattern and themarkforming components thereby are brought into reactive contact,producing a distinctive mark.

The mark-forming components generally comprise a chromogenic materialand a polymeric material reactive with the chromogenic material toproduce a distinctive mark (through acidic groups). The chromogenicmaterial in unreacted state preferably should be colorless, though lighttones may be tolerated, and capable of color change to a strongdistinctive color upon reactive contact with the polymeric materialmark-forming component. While combinations of chromogenic material andpolymeric material from any of the known color-producing systems may beused, the invention has particular utility in regard to thecolor-forming system wherein the chromogenic material is a base and thecomplementary polymeric material is acidic; i.e., where the color orchange in color is brought about by the acidic action of the polymerconstituent on the chromogenic material. The invention will hereafter bedescribed and illustrated by reference to said base-acid system.

Examples of suitable basic materials having chromo genic groups arediaryl phthalides; leucauramines; acyl auramines; a,fl-unsaturated arylketones; basic mono azo dyes; Rhodamine B Lactams such asN(p-nitrophenyl) Rhodamine B Lactams; polyaryl carbinols; and 8' methoxybenzoindolinospiropyrans, which may be identified as (8' methoxy BIPS).Illustrative compounds of each group are diaryl phthalides:3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (Crystal VioletLactone, hereinafter refered to as CVL) and3,3-bis(4-dimethylaminophenyl) phthalide (Malachite Green Lactone,hereinafter referred to as MGL); leucauramines; the N-halophenylderivatives of leucauramine disclosed in US. Pat. No. 2,828,341, issuedto Clyde S. Adams, Marjorie I. Cormack, and Mary Lou Frazier on Mar. 25,1958; and the N-al'kylhalophenyl derivatives of leucauramine disclosedin US. Pat. No. 2,828,342, issued to Clyde S. .Adams and Marjorie J.Cormack on Mar. 25, 1958, said patents being incorporated by referenceherein, particularly =N-(2,5 dichlorophenyl) leucauramine; acylauramines: N-benzoyl aruramine; and N-acetyl auramine; c n-unsaturatedaryl ketones: dianisylidene acetone; dibenzylidene acetone; andanisylidene acetone; basic mono azo dyes:p-dimethylaminoazobenzene-o-ca.rboxylic acid (Methyl Red); 4-aminoazobenzene (Oil Yellow AAB); and 4phenylazo-l naphthyla-mine;Rhodamine B Lactams: N-(p-nitro phenyl) Rhodamine B Lactam (hereinafterreferred to as RBL); polyaryl carbinols: bis(p-dimethylaminophenyl)methanol, called Michlers Hydrol; Crystal Violet carbinol; and'Malachite Green carbinol; 8-methoxy BIPS;

8" methoxybenzoindolinospiropyran;4,7,8'-trimethoxybenzoindolinospiropyran; and p-dirnethylaminostyryl oin In the base-acid'color system, as stated above, the polymeric'mark-forming component(s) chosen must be acidic relative to 'the basicchromogenic compound and reactive' with the chromogenic material toeffect distinctive color formation or color change. Moreover, thepolymeric mark-forming component(s) should: have a common solubilitywith the chromogenic material ina't least one liquid solvent. v 1 V f-Itshould be understood that the scope of the inventionincludes in a singlesystem" the utilization'of'one or more chromogenic materials on one handand one or more polymeric mark-forming components on the other hand.Thus, for example, several chromogenic materials may befus'e'd with thesame or different polymeric materials and vice versa. Y I

As mentioned above, the solvent is maintained in physical isolation inminute 'droplets until'such time as it is'rele'ased by applicationof'pressure. This may be accorriplished by a'ny'of several known"techniques, but

preferably isolation is' maintained by individual encapsulation of thesolvent droplets in a microcapsule according 'to the proceduresdescribed, for example, in United States Patents Nos; 2,712,507, issuedto Barrett K. Green on July 5, 1955; 2,730,457, issued to Barrett K,Green and Lowell 'Schleicher on Jan. 10, 1956; 2,800,457, issued toBarrett K. Green and Lowell Schleicher on July 23, 1957; and 2,800,458,issued to Barrett K. Green on July 23, 1957, reissued as Reissue PatentNo. 24,899 on 'Nov. 29, l960."Ihe microscopic capsules, when disposedwithin and/or on a support sheet as a profusion in contiguousjuxtaposition, are rupturable by pressure, such as the pressuresnormally attending writing and printing operations.

The particular material(s) chosenas the wall material of themicrocapsule, in addition to being pressure-rupturable, must beincompatible with the contents of the capsule and the mark-formingcomponents, in the sense that the wall material retains its integrityunder normal storage conditions until such time as it is released by theapplication of marking pressure.

upper limit is 15 microns and most preferably from 5 to 10 microns.

Any polymeric material having the aforementioned ;wholly'.hydrolyzedstyrene-maleic anhydride copolymers and ethylene-maleic anhydridecopolymers, carboxy polymethylene (Carbopol 934), and wholly orpartially .mer are specified as typical of the reactive acidic polymericmaterials.

Among the phenol-aldehyde polymers found useful are members of the typecommonly referred to asnovolacs,

hydrolyzed vinyl methyl ether maleic anhydride copolywhich arecharacterized by solubility in common organic solvents and which are, inthe absence of crosslinking agents, permanently fusible. Another group[of useful phenol polymeric materials are alkylphenol-acetylene resins,likewise soluble in common organic solvents and possessing permanentfusibility in the absence of, being treated by cross-linking materials.Generally, the phenolic polymer material useful in practicing thisinvention is characterized by the presence of free hydroxyl groups andthe absence of groups, such as methylol, which tend to promoteinfusibility or cross-linking of the polymer, and

- by their solubility in organic solvents and relative insolu bility inaqueous media.

Resoles, if they are still soluble, may be used, though snbjecf tochange in properties upon aging. I

A laboratory method useful in the selection of suitable phenolic resinsis a determination of the infra-red absorption pattern. It hasbeenfound; that phenolic resins showing an absorption in the 3200-3500cmrregion (which is} indicative of the free hydroxyl groups) and nothaving an absorption in the 1600-1700 cm.- region are suitable. Thelatter absorption region is indicative of the de-sensitization of thehydroxyl groups-and consequently makes such groups unavailable forreaction with the chromogenic materials.

The preparation of the phenolic-formaldehyde p'olymeric materialssuitable for practicing this inventionis described in Industrial andEngineering Chemistry, volume 43, pages 134 to 141, January 1951, and aparticular polymer thereof is described in Example 1 of. U.S. Pat. No.2,052,093, issued to Herbert Hiinel on Aug. 25, 1936, and-thepreparation of'the phenol-acetylene polymers is described in Industrialand Engineering Chemistry,volnine 41, pages 73 'to 77, January 1949.

The preparationof the maleic anhydride copolymersis described in theliterature, such as, for example, one of the maleic anhydride vinylcopolymers, as disclosed in the publication Vinyl and Related Polymers,by Calvin E. Schildknecht, secondprinting, published April 1959 by JohnWiley & Sons, Incorporated. See pages 65'to'68 (styrene-maleic anhydridecopolymer),628 to 630 (vinyl methyl ether-maleic anhydride -cop'olymer),and 530 to 531 (ethylene-maleic anhydride copolymer).

The liquid solvent chosen must be capable of dissolving-the mark-formingcomponents. The solvent may be volatile or non-volatile, and a single ormultiple component solvent may be used which is wholly or partiallyvolatile. Examples of volatile solvents useful with the aforedescribedbasic chromogen-acidic polymer markformingcomponents aretoluene,petroleum distillate, perchloroethylene, and xylene. Examples ofnon-volatile solvents are high-boiling-point petroleum fractions andchlorinated diphenyls.

' Generally, the solvent chosen should be capable of dissolving at least1%, on a weight basis, of the chromogenic material, preferably in excessof 2%, and a corresponding amount of polymeric material to form aneflicient reaction. However, in the preferred system, the solvent shouldbe capable of dissolving an excess of the polythe mark-forming reactionor diminish'the intensity of the mark, in which case the solvent chosenshould be sufficiently vaporizable to-assure its removal from thereaction site after having, through solution, brought the mark-formingcomponents into intimate admixture, so that the mark-forming contactproceeds.

Inasmuch as the mark-forming reaction requires an intimate'mixture ofthe components to be brought about through solution of said components,one or more of the mark-forming components may be dissolved in theisolated solvent droplets, the only requirement being thatat least oneof the components essential to the mark-forming reaction be maintainedundissolved by a droplet until the droplet'is released by application ofpressure.

In the usual case, the mark-forming components are so chosen "as toproduce a mark upon application of pressure at roomtemperature (20to 25degreescentigrade).

. However, the present invention includes a system'in which i thesolvent component is not liquid at temperatures around room temperaturebut is liquid and in condition for forming solutions only at elevatedtemperatures.

The support member on which the components of the system are disposedmay comprise a single or dual sheet assembly. In the case where allcomponents are disposed on a single sheet, the record material isreferred to as a self-contained system. Where there must be a migra tionof the solvent, with or without mark-forming component, from one sheetto another, the record material is referred to as a transfer system.(Such a system may also be referred to as a couplet system, in that atleast two sheets are required and each sheet includes a component, orcomponents, essential to the mark-forming reaction.) Where a copiousamount of the colored reaction product in liquid form is produced on asurface of one sheet, it may produce a mark by transfer to a secondsheet as a colored mark.

.In the preferred case, where microcapsules are employed, they may bepresent in the support material either disposed therethroughout or as acoating thereon, or both. The capsules may be applied to the sheetmaterial while still dispersed in the liquid vehicle in which they weremanufactured, or, if desired, separated and the separated capsulesthereafter dispersed in a solution of the polymeric component (forinstance, 30 grams of water and 53 grams of a 1% aqueous solution ofpolyvinyl methyl ether maleic anhydride) to form a coating compositionin which, because of incompatibility of the solution and the capsules,both retain their identity and physical integrity. When this compositionis disposed as a film on the support material and dried, the capsulesare held therein subject to rupture to release the liquid contained.This latter technique, relying on the incompatibility of themicrocapsule and the dispersing medium of the film-forming mark-formingcomponent, allows for a method of preparing a sensitive record coatingwith the capsules interspered directly in a dry film of the polymericmaterial as it is laid down from the solution. A further alternative isto disperse in a liquid medium one or more mark-forming components,insoluble therein, and disperse in said medium the insolublemicrocapsules, with the result that all components of the markformingsystem may be disposed on or within the support sheet in the oneoperation. Obviously, the several components may be appliedindividually.

The arrangement and the physical state of the components of themark-forming system in relation to support material will be furtherdiscused hereafter, and specific arrangements are shown in the drawings.

The respective amounts of the several components will vary, dependingprimarily upon the nature of the materials and the architecture of therecord material unit. Suitable amounts include, in the case of thechromogenic material, 0.03 to 0.075 pound per ream (a ream in thisapplication meaning five hundred sheets of 25" x 38" paper, totalling3,300 square feet), the preferred amount being 0.05 pound per ream; inthe case of the solvent, 1 to 3 pounds per ream; and in the case of thepolymer, /2 to 3 pounds per ream. One half pound per ream of 3300 sq.ft. is equivalent to 0.45 pound per 3000 sq. ft. ream. In all instances,the upper limit is primarily a matter of economic consideration.

Of the drawings:

FIG. 1 is a highly diagrammatic representation of a couplet system withadjacent faces of the sheets sensitized with mark-forming components,the bottom surface of the overlying sheet having a coating ofpressure-rupturable capsules containing a solution of the basicchromogenic component, and the acidic component being a phenolicpolymeric material coating on the upper surface of the lower sheet,there to make a colored mark as by the use of a stylus, a typecharacter, or other pressurewriting means applied to the couplet.

FIG. 1a is a highly diagrammatic cross-section of a portion of atransfer system being subjected to a stylus impression.

FIG. 2 is a representation, in a series of highly diagrammatic sectionsthrough a self-contained record sheet unit (views V-XIII) or a coupletunit of two paper sheets (views I-IV, XIV, and XV), showing the physicalarrangement of the various components which are identified by characterstranslatable according to the legend accompanying them. These views showthe disposition of the mark-forming components in symbol form toillustrate some constructions of record material coming within the scopeof the invention. Other constructions coming within the principle of theinvention are possible, some being set forth in the examples to follow.

FIG. 1 generally shown a two-sheet unit in perspective in which theunder side of the over-sheet is supplied on the surface, or near it,with a profusion of minute pressure-rupturable microcapsules eachcontaining a liquid droplet. The droplets are released on rupture of thecapsules in data-representing configuration in printing or writingoperations, as shown in FIG. la. The liquid of the released droplets istransferred in the pattern of the data configuration to the top of theunder-sheet, which is supplied with a material co-reactant with thereceived liquid to produce a distinctively-colored mark corresponding tothe configuration of the pressure pattern. In the drawing, the surfaceof the under-sheet is marked with symbols (see legend, FIG. 2)indicating a polymeric reactant film material (a novolac type ofphenolic polymer material having an acid-reacting OH group, forinstance), and the capsules on the rear of the over-sheet are markedwith symbols indicating a contained liquid solution of chromogenicmaterial (CVL or MGL, for instance). However, if desired, the capsulesmay contain the polymeric material in liquid solution, and the topsurface of the undersheet may be supplied with the chromogenic materialin particulate form. A representative number of architecturalarrangements of theseveral components with respect to support materialare shown in FIG. 2, views I to XV.

As noted generally above, these capsules may be applied to a supportsheet from an aqueous slurry in which they were made, with an amount ofaqueous vehicle material added or removed to give the slurry propercoating consistency. The slurry may have binder material added, ifconsidered necessary. Paper coated with capsules of microscopic size andcontaining printing fluid, and the method of making them, are shown inUS. Pat. No. 2,712,507, which issued July 5, 1955, on the application ofBarrett K. Green, and which has been mentioned before.

In the instance where the mark-forming components are interspersedthroughout a single support sheet material (so-called self-containedunit), the following techniques or procedures have been found useful:

In FIG. 2, views Vb through Vd, where either the liquid solvent or oneor more of the mark-forming components are disposed on the surface ofthe support member, and wherein the remaining components of the systemare disposed within the support member, this architecture may beachieved by supplying in the furnish the component to be interspersed inthe support sheet, then having the furnish pass onto the Fourdrinierwire. After the formed sheet is dried, the remaining necessary componentor components may be coated thereon. In FIG. 2, views VII, IX, and XIII,the various components are coated individually or simultaneously ontothe support member. In FIG. 2, views VIII, X, XI, and XV, the severalcomponents are interspersed within the support sheet according to thetechnique outlined above for views Vb through Vd.

The slurry of capsules may be applied to a wet web of paper as it existson the screen of a Fourdrinier paper machine, so as to sink into thepaper web a distance depending on the freeness of the pulp and the watercontent of the web at the point of application.

The capsules may be placed directly in the paper pulp furnish before itis applied to the paper machine screen, and thus appear throughout thethickness of a sheet (see FIG. 2, views VIII, X, XI, XII, and XV).

As the liquid content of these capsules of views VIII and XI, forinstance, must make contact with the dry polymeric material component ofthe record unit of this type, the quantity of capsules, the quantity ofretained liquid, and the availability of the liquid to make contact withthe dry particles are details that must be tailored to the desiredconstruction and performance standards desired. The same criteria must.be met wherever the liquid is situated or whatever it contains.

The presence of droplets of isolated liquid is. of the essence of theinvention, which does not reside solely in the isolation of them incapsules, as the liquid droplets may be retained as a discontinuousemulsion droplet phase in a' continuous film of pressure-rupturablematerial. Such film-holding of droplets that are released by writing orprinting pressures is a well-known expedient, disclosed in US. Pat. No.2,299,694 and in US. Pat. No. 2,374,862, issued to Barrett K. Green onOct. 20,- 1942, and May 1, 1945, respectively, and are made bydispersing the oil droplets in a solution of polymeric film materialwhich is applied to a record sheet and dried. Wherever reference is madeto the isolation of liquid droplets in this application, it includesthis continuous -film structure as a full equivalent of capsules, exceptthat the liquid is more impermeably retained in the capsules, and theymay be treated as particles for incorporation into the paper-machinefurnish. Thus, where the views of FIG. 2 show circles as the droplets onor in a support sheet, it means not only capsule structures but filmswhich hold a multitude of droplets for localrelease in an area subjectto pressure.

View Ia of FIG. 2 shows the relative relation of markforming componentsdisposed in a two-sheet unit, wherein the sheet that receives thedroplets has buried in itsolid particles of both components, which,being water-insoluble, may be incorporated in a paper sheet as it isbeing made. The isolated solvent is applied to the under side of theover-sheet as droplets in sufiicient amount to penetrate among the paperfibers of the under-sheet to mutually dissolve the particulatecolor-forming components disposed there.

To make a dispersion of water-insoluble particulate polymeric material,a solution thereof in an evaporable solvent is introduced into twice asmuch water and agitated while the evaporable solvent is blown off by anair blast. This leaves an aqueous colloidal dispersion slurry of thepolymeric material, which may be applied to the paper so as to leave asurface residue, or the slurry may be applied to paper at the size-pressstation of a paper-making ma= chine by roller. In another method ofmaking a polymersensitized sheet, the water-insoluble polymer is groundto the desired particle size in a ball mill with water, preferably witha dispersing agent, such as a small quantity of sodium silicate. If abinder material of hydrophilic properties is ground .with the phenolicmateriaLthe binder itself may act as a dispersant. If desired, an amountof binder material of up to 40%, by weight, of the employed amount ofthe polymeric material may be added to the ball-milled slurry ofmaterials, such binder materials being of the paper-coating binder classincluding gum arabic, casein, hydroxyethylcellulose, and latex (such asstyrenebutadiene copolymer). If desired, oil adsorbents in the form offullers earths may be added to the polymeric materal particles .toassist in retaining, in situ, the liquid droplets to be transferred toit in data-representing configuation, for the purpose of preventingbleeding of the print.

Another way of applying the chromogenic or polymeric materialindividually to a single sheet of paper is by immersing a sheet of paperin a 1% to 10% solution of the material in an evaporable solvent.Obviously, this must be done alone for each reactant because, if theother reactant material were present, it would result in a prematurecoloration over the sheet area. A dried sheet with one component thenmay be coated with a solution of the other component, the solvent ofwhich is a non-solvent to the already-supplied component.

examples The polymeric material may be dissolved inink compositionvehicles to form'a printing ink. of colorless character and, thus, maybe used to spot-print aproposed record sheet unit sensitized forrecording in a reactionproduced color in those areas by application of asolution of the chromogenic material. a

In the case of phenolic polymer, a printing ink may be made of up to byweight, of the phenolic polymeric material in a petroleum solvent to aviscosity suitable for printing purposes.

In all the views, which in themselves constitute specific constructionexamples without naming specific color-reactants, it is to beunderstood, the showing is i'nexaggerated form, as the record materialsin their manufactured form are hardlydistinguishable from ordinarycoated-paper printing stock, the normal coloration being that of thebase sheet stock, and the sensitizing materials as to particle size,when particles areinvolved, being small enough to escape observation,but close enough to each other to afford a good recording surface orback ground surface against which the record can be visually sensed f'herelative amounts of components toibe used' a re the most convenient 'andeconomical amounts consistent with proper visibility of the recordeddata. The resolution of the recorded data'is, among otherthings,dependent on particle size, distribution and amount of particles,liquid solvent migration, chemical reaction'efiiciency, and otherfactors, all of which are'things that may be worked'ou t empirically byone familiar with the art, and which do not determine the principle ofthe invention, which, in part, involves means for enabling the bringinginto solution, by marking pressure, of two normally solid components ina common liquid solvent component held isolated as liquid droplets,preferably in marking-pressurerupturable capsules having film walls, or'else held isolated in a continuous marking-pressure-rupturablefilm as adiscontinuous phase.

In the arrangement of material components of a multiple-sheet unit whichrequires one or more components to be on the back of an overlying sheetsuch as that shown in FIG. 2, views I to IV, if the co-reactant materialwere supplied on the otherwise uncoated back surface of the under-sheet,it could serve as the middle sheet of a stack of three or more sheetstofurnish another rendition of the recorded data. Thus, if in FIG. 2,view I, the undersheet were coated on its back surface withsolvent-containing capsules, it could transferthe released solvent foraction'with the top surface of a second uuderrsheet, and so on. In thisrespect, the action between the back of' the middle sheet and thesensitizing material of the second under-sheet, it could serve asthemiddle sheetof a" stack of an intentionally-made difference in theselection of components materials, or an intentionally-made difference.

in the physical arrangement of the components between the back of thesecond sheet and the top of the third sheet according to the variousspecies of the invention shown in the drawings and disclosed in thespecification.

The invention is further illustrated in the following EXAMPLE I.

Preparation of sheet having the chromogenic material In this example asmade, the chromogenic material was CVL, and the solvent comprised twoparts by weight of chlorinated diphenyl (Aroclor 1242),. and one part byweight of petroleum solvent having a boiling range of 9v 390 to 496degrees Fahrenheit (Shell Dispersol). A 3% solution of CVL was thenmicroencapsulated in the following manner:

(a) Emulsification: Into a Waring Blendor were weighed 53 grams of 1%,by weight, solution of polyvinylmethylether maleic anhydride copolymerin water, 30 grams of water, and 113.7 grams of 11% aqueous gelatin sol.With the blendor running at slow speed, 200 grams of the CVL solution(internal phase) was added, and the blendor was operated until theparticle size of the dispersed internal phase was about 5 microns orless.

(b) Coacervation: 75.8 grams of 11% aqueous gum arabic sol was slowlyadded, with stirring, to the internalphase-gelatin-sol emulsion (a).After thorough stirring, the contents of the blendor was passed into avessel and diluted by the addition of 600 grams of water at atemperature of 55 degrees centigrade. The pH was then adjusted to about9.0 by the addition of sodium hydroxide. The pH was lowered at the rateof 0.1 pH unit per minute by the addition of 14% aqueous acetic aciduntil a pH of 4.6 was reached, to thereby cause a liquid coacervate wallto separate and deposit about the dispersed internal phase.

.;(c) Hardening: After the encapsulation was completed, the system waschilled to degrees centigrade to gel the coacervate walls, and 6.5milliliters of 25% glutaraldehyde solution was added and allowed to stirfor ninety minutes. The capsules so produced were then coated on asupport sheet (transfer sheet) to yield a dried coating of 4 pounds perream of 500 sheets 25 by 38 inches.

Preparation of sheet having the polymeric material The polymericmaterial was prepared in the following manner:

170 grams (1 mole) of paraphenylphenol, 65 grams of 37% aqueousformaldehyde, 10 cubic centimeters of concentrated hydrochloric acid 371 gram of oxalic acid dihydrate, and 40 cubic centimeters of Water wereadded to a resin kettle and refluxed at the boiling point of the waterfor eight to twelve hours, after which the reaction mass was allowed tocool, and the water layer was decanted. The resin mass then wasdistilled under reduced pressure (bench aspirator) until the flasktemperature reached 120 to 130 degrees centigrade. Following the vacuumdistillation, the resin mass was poured into a stainless steel tray andallowed to cool. A second support sheet (receiving sheet) wasimpregnated with the polymer by being dipped into a 4% xylene solutionof the resin and dried.

Upon bringing the capsule-coated surface of the associated supportsheets into contiguous relation to the polymeric-impregnated sheet andapplying a pressure stroke to the uncoated side of the sheet containingthe microcapsules, a vivid blue mark was produced on the polymerbearingsupport sheet.

EXAMPLE Ia In distinction to Example I, the present example illustratesthe invention wherein the polymer is present on the receiving sheet inparticulate form and as a coating on the surface of the support sheet,as opposed to the impregnation, resulting from the dipping step, set outin Example I. The preparation of the microcapsules, the solution of thechromogenic material, and the coating of the capsules on the transfersheet were the same as in Example I; likewise, the preparation of thepolymer. The receiving sheet was coated with the polymeric material inthe following manner:

5 grams of the polymer of Example I, 1.5 grams of gum arabic, and 43.5grams of water were ball-milled for approximately eighty hours to aparticle size of under five microns. The resulting aqueous dispersionwas then coated onto one side of a receiving sheet. Upon contacting thesheet surfaces as in Example I and applying pressure, a vivid blue markwas produced on the receiving sheet.

10 EXAMPLE Ib This example illustrates the invention wherein thepolymeric material is present in particulate form in the support sheetbut is substantially evenly distributed throughout the body of thesheet.

The preparation of the microcapsules, the solution of chromogenicmaterial, and the coating on a transfer sheet was carried out as inExample I; likewise, the preparation of the polymer. The polymer wasincorporated in the receiving sheet in the following manner:

The dispersion of Example Ia, having had added thereto a suflicientquantity of a pulp dispersion to produce a five-to-one ratio of pulp topolymer solids, and then having been diluted to a final solids contentof 0.5%, was subsequently passed onto a Fourdrinier wire in order toform a sheet. The sheet so formed was placed in contact with the capsuleside of the microcapsule-coated sheet, and, upon application ofpressure, a blue mark was formed on the polymer-bearing sheet.

EXAMPLE II The following example illustrates the invention wherein thepolymer is the p-cyclohexyl phenol-formaldehyde condensation product.

CVL was the chromogenic material used, and the preparation of the CVLsolution and its microencapsulation were the same as in Example I.Likewise, the support sheet was coated with the microcapsules as inExample I.

The polymer was prepared as follows:

176 grams of p-cyclohexyl phenol, 65 grams of 37% aqueous solution offormaldehyde, 10 cubic centimeters of concentrated hydrochloric acid(37%), and 40 cubic centimeters of water were added to a resin kettleand refiuxed at the boiling point of the water for eight to twelvehours, after which the reaction mass was allowed to cool, and the Waterlayer was decanted. The resin mass was then distilled under reducedpressure (bench aspirator) until the flask temperature reached todegrees centigrade. Following the vacuum distillation, the resin masswas poured onto a stainless steel tray and allowed to cool.

A receiving sheet was treated as in Example I with a solution of saidpolymer, and, after bringing the surfaces of the support sheets intocontiguous juxtaposition relation and applying pressure thereto, a bluemark was formed on the polymer-bearing sheet.

EXAMPLE Ha The transfer sheet was prepared as in Example I.

The polymer used was the p-tertiary-amylphenol-formaldehyde condensationproduct. Said polymer was prepared according to the method of ExampleII, using one mole of the p-tertiary-amyl phenol compound to .8 mole offormaldehyde.

A receiving sheet was prepared according to the method described inExample I, using the phenol-formaldehyde polymer of this example.Application of pressure to the untreated side of the transfer sheetproduced a blue mark on the receiving sheet.

EXAMPLE 11b The transfer sheet was prepared as in Example I.

The polymer used was the p'nonyl-phenol-formaldehyde condensationproduct. Said polymer was prepared according to the method of ExampleII, using one mole of the p-nonyl-phenol compound and .8 mole offormaldehyde.

The receiving sheet was prepared as in Example I, using thep-nonyl-phenol-formaldehyde polymer. Application of pressure as inExample Ila produced a blue mark on the receiving sheet.

EXAMPLE III is *disclosed as being reacted with acetylene at elevated 1temperature and pressure.

A 4% solution of the para-tertiary-butyl phenol-acetylene resin inbenzene was prepared, and a receiving sheet was impregnated therewith bybeing dipped into the solution. Upon the application of pressure on thesupport sheets held in contact position, a blue mark was formed on thepolymer-bearing sheet.

EXAMPLE IIIa As an alternative to the impregnation procedure of ExampleIII, a support sheet was coated on one side with an .aqueous dispersionof said para-tertiary-butyl phenol-acetylene resin. The dispersion wasprepared as follows:

20 grams of resin, 3.5 grams of gum arabic, and 50 grams of water wereball-milled for eighty-four hours, and the dispersion was coated on asheet and dried. The polymer-coated sheet, upon contact with thetransfer sheet having the microencapsulated chromogenic material,produced a colored mark upon application of marking pressure to thetransfer sheet.

In Examples IV to VIII which follow, different chromogenic material wasused in conjunction with p-phenyl phenol-formaldehyde polymer. In allcases, the polymer and the receiving sheet were prepared according totheprocedure of Example I.

EXAMPLE IV 8-methoxy BIPS was the chromogenic material, the solutionbeing made by dissolving 4 grams of the BIPS compound in '100 cubiccentimeters of chlorinated diphenyl (Aroclor 1242).

The BIPS solution was encapsulated in the following manner:

(a) Emulsification: Into a Waring Blendor were placed 80 cubiccentimeters of the BIPS solution, 80 cubic. centimeters of 11% aqueousgelatin sol, and 80 cubic centimeters of 11% aqueous gum arabic sol; thepH was adjusted to 6-6.5; and the blendor was operated until the BIPSinternal phase droplet size Was microns or less, to thereby emulsify theBIPS solution in the gelatin-gumarabic sols.

(b) Coacervation: The emulsion of step (a) was transferred to a beaker,and, with constant stirring, the emulsion was diluted by the addition ofwater to make one liter. The pH of the mass was then slowly lowered bythe addition of acetic acid until the visual test of cloudiness, asoutline in Green and Sehleicher United States Patent No. 2,800,458,issued July 23, 1957, indicated that coacervation was complete.

(c) Hardening step: The mass was then chilled to 10 degrees centigradeand allowed to stand for one hour at this temperature. Subsequently, 5cubic centimeters of glutaraldehyde solution was added, and the entiremass was stirred overnight before use.

The capsules so produced were then coated on a transfer sheet accordingto the technique of Example I. Upon application of pressure tocontiguously-disposed transfer and receiving sheets, a brown mark wasproduced.

ample IX and a transfer sheet bearing microcapsules of 12 1 EXAMPLE VAll components were the same as iii" Example IV except that thechromogenic. material wasN-benzoyl auramine, which material wasdissolved in 2/1 ratio by volume of chlorinated diphenyl '(Aroclor 1242)and petroleum distillate, boiling range 316 to 358 degrees Fahrenheit(Shell 360), to give a 1% N-benzoyl auramine solution. The record unitsystem containing N-benzoyl auramine as the chromogenie material gave agreen-blue mark upon appli-, cation of pressure.

EXAMPLE VI All materials and procedures'were the, same as in Example IVexcept that the chromogenic material-was pdiphenyl aminostyrylquinoline.Two grams of the chromogenic material'was dissolved in a sufficientamount or equal parts by volume of chlorinated diphenyl and petroleumdistillate (boiling range 316 to 358 degrees Fahrenheit) to yield a 2%solution. A record unit using the chromogenic material in this exampleyielded a red-brown mark upon the application of pressure in the usualmanner.

EXAMPLE VII I All materials and procedures were the same as in ExampleIV except that the chromogenic material was'a 3 by weight, solution ofI- l-(2,5-dichl :\ro phenyl) leucauramine in a 2/1 weight ratio mixtureof chlorinated diphenyl in petroleum distillate (boiling range 385 to496 degrees Fahrenheit) Again, a record unit containing the indicatedch'romogenic material produced a blue mark upon application of pressurein the usual manner.

EXAMPLE VIII The materials and procedures of this example were the sameas in Example IV except that the chromogenic material was 3% of MichlersHydrol 1112/1 weight ratio mixture of chlorinated diphenyl and petroleumdistillat (boiling range 385 to 496 degrees Fahrenheit).

EXAMPLE 1x Five grams of a partially-hydrolyzedethylene rnalei'canhydride copolymer (Monsanto DX- 84381),1.5 grams Ethocel (HerculesPowder Company, Ethyl Cellulose, Type N 14, 14.1% Ethoxyl), and 44.25grams of carbon tetrachloride were admixed to give a dispersion 'of thecopolymer in the carbon tetrachloride. Styrene-maleicanhydriedcopolymer, vinylmethylether-maleic anhydride copolymer, and carboxypolymethylene are useful substitutes 'for the ethylene-maleic anhydriedcopolymer but are not EXAMPLE X A record unit comprising the receivingsheet of Ex- N- (2,5-dichlorophenyl) leucauramine gave a blue mark uponapplication of pressure.

EXAMPLE XI A record unit comprising the receiving-sheet of -Example IXand a transfer sheet bearing microcapsules of CVLgave a blue mark uponapplication of pressure.

' EXAMPLE XII I A record unit comprising the receiving sheet' of ExampleIX and a transfersheet bearing'microcapsules of Michlers Hydrol gavea'blue mark upon application of pressure.

13 EXAMPLE XIII The dispersions of capsules and polymer as a mixturewerethen coated upon a support sheet and dried.

Upon application of pressure to the support sheet, a mark was producedon the coated surface according to the pressure pattern.

EXAMPLE XIV This example specifies an architecture wherein one or moreof the components of the system are interspersed throughout the supportmember and the remaining components are coated on the surface asdepicted in views Vb, Vc, and Vd of FIG. 2.

If the chromogenic material is in the body of the sheet, it is appliedas a part of the aqueous furnish of fiber to the Fourdrinier wire, andthe same method is used in introducing the polymeric material into thebody of the sheet. CVL was used as the chromogenic material, and aparaphenylphenol formaldehyde condensation product was used as theacidic polymer. The top coatings are applied from aqueous dispersions ofthe particles or capsules in the usual manner. The solvent waschlorinated diphenyl (Aroclor 1242). Upon the application of pressure tothe support sheet, a mark was produced according to the pressurepattern.

EXAMPLE XV This example demonstrates an architecture wherein the severalcomponents of the system are interspersed throughout the support sheet(FIG. 2, views X, XI, and XII).

The chromogenic material was CVL, the solvent was chlorinated diphenyl(Aroclor 1221), and the polymeric material was paraphenylphenolformaldehyde condensation product. The polymeric material wasencapsulated according to the procedure of Example IV. Upon theapplication of pressure to the finished sheet, a mark was producedaccording to the pressure pattern.

The several components were dispersed in water and supplied to theFourdrinier wire with the furnish.

EXAMPLE XVI This example demonstrates a self-contained unit wherein theseveral components of the system are coated onto the support member andfurther wherein the several components are distributed within acontinuous film of the polymeric material, as shown in FIG. 2, view VII.The chromogenic material was CVL, which was dissolved in chlorinateddiphenyl (Aroclor 1221) and encapsulated according to Example I, withthe exception that the capsules were spray-dried to produce afree-flowing powder. The polymeric material was a paraphenylphenolformaldehyde condensation product. A xylene solution of the polymericmaterial was prepared, and the dry powdered capsular product wasdispersed therein. The dispersion was then coated on the support sheetmaterial and dried. Upon application of pressure to the coated sheet, amark was produced in accordance with the pressure pattern.

The chosen polymeric material may have film-forming properties, with theconsequent attainment of high resolution of recorded data that attendsthe use of a continuous film.

' Generally, the polymeric material at the marking sites will be presentas a film subsequent to the production of the mark-forming reaction. Thepresence of the polymer in film form provides several advantages;namely, that the zone of marking has a protective film surrounding it,which substantially diminishes removal of the mark by abrasive action.Additionally, in the case of the preferred material-namely, the phenolicpolymersthe water-insolu-bility of the polymer will precludedecolorization by atmospheric moisture attack.

' Where the-polymeric material is disposed originally on the supportsheet-member as a continuous film, it provides large surface area ofreactive material in a form that is readily soluble. Additionally, thepresence of the polymer in solution'form provides for greater ease ofadaptability to existing application apparatus, such as, for example, aprinting ink applicator. Finally, as compared with prior-art systems,the polymer, because of its great afiinity for the substrate,substantially reduces the so-called picking problem associated withcoatings of particulate materials such as attapulgite.

Under some circumstances, it may be desirable to have the chromogenicmaterial present as a mixture of compounds which yield dilferent hues onreaction with the polymeric material, such hues blending to produce acompound visual efiect. For instance, a mixture of a compound yielding ablue color and one yielding a red color would visually combine to a darkpurple approaching blackness.

It also may be desirable to mix polymeric components for economicreasons or reaction characteristics. Thus a mixture of the phenolicpolymers specified may be used with one or more of the chromogenicmaterials to produce a desired end product.

It 'becomes apparent that the invention described is not limited in theuse of single pairs of reactant compounds, or even in regard to singleand double sheet systems, and that one sheet may have data markedthereon in one color and the next underlying sheet may yield the samemark configurations in same or different colors.

What is claimed is:

1. A pressure-sensitive record unit comprising:

(a) support sheet material,

(b) mark-forming components, and a pressure-releasable liquid organicsolvent for both said markforming components arranged in contiguousjuxtaposition and supported by said sheet material,

(0) at least one of the mark-forming components being maintained inisolation from other mark-forming component(s),

(d) said mark-forming components comprising at least one basicchromogenic material and at least one phenolic polymeric material whichis acidic relative to the basic chromogenic material and reactive withthe basic chromogenic material to effect distinctive color formation orcolor change, said phenolic polymeric material being a condensate of aphenol and an aldehyde, said phenolic polymeric material also beingpermanently fusible in the absence of added cross-linking agents andbeing further characterized by the presence of free-hydroxyl,acid-reactive groups and solubility of at least 2% by weight in saidliquid organic solvent, which components, on pressure release of theliquid organic solvent, are brought into reactive contact by mutualsolution in the released liquid organic solvent.

7 2. The record unit of claim 1, wherein the aldehyde is formaldehyde.

3. The pressure-sensitive record unit of claim 1 where-- in the phenolicpolymeric material is a condensate of a para-substituted phenol and analdehyde.

4. The pressure-sensitive record unit of claim 1 wherein the phenolicpolymeric material is a condensate of a phenol having a hydrocarbonsubstituent in the para position and an aldehyde.

; g 9.; The. record; m: 1te1' ial= of; claimv 2 wherein. the henolicpolymeriqmaterial-is:present in the -sheet material in an amountofabout- 0:5 to 3 pounds per ream.

Relerences Cited- UNIFIED "STATES? PATENTS rimary Examiner

